Border to Macedonia are open and acces to the country is easy.

Holders of EU passports don't need visa, same applies to citizens of USA, Canada, Australia, New Zealand, Japan, Tunisia, Egypt (plus some others list available on stay is visa free for up to 90 days

For other visa requiraments please check 

Also if you have a valid Schengen visa, but you require a visa for Macedonia, you can use that Schengen visa for stay up to 14 days.

All foreign nationals are required to sign up with the police, which is mainly done by the hotels and guest houses when you check in. If you are planning to do DIY holiday and you are not staying at the hotel then you have 48 hrs to check in with the police.

A failure to do so can result in penalty of €1000 at the time of departure.

Nationals of Serbia, Albania, Montenegro, can visit Macedonia only using their ID cards same is valid for Macedonians visiting those countries.

Russian, Ukrainian, Moldovan and Belorussian nationals don't need a visa to enter the country, however they need to show a hotel voucher ( invitation letter) for free entrance, here again reciprocity is at play, same rules aply for Macedonians travelling to those countries.